RTF is a global modification that replaces all towns in the game.

The four elements are clearly inspired by Heroes of Might and Magic III, but from the perspective of a fan of the third game, this distribution of specific spells is heresy.

Drawing inspiration from the third game is one thing, copying it is another. The third game also had its own shortcomings. And here, even the universe is different (the third game's universe cannot be simply copied).
Personally, I see the magic of four elements as a way to diversify the schools: in Heroes of Might and Magic V, each school has such a narrow specialization that a whole range of problems arise, starting from balance (different schools will work with different efficiency at different stages of the game, no matter what), and ending with playing single-player scenarios (where darkness dominates in 90% of cases, killing the diversity of gameplay).
Here, I saw an attempt to make the schools more diverse, while keeping the specializations within reasonable limits. To be honest, I really like this idea and I internally supported the developers.